Piano Tuner
Check individual piano and keyboard notes against equal temperament, with a responsive key strip and reference tones.
Two octaves at a time. All 88 keys on a phone would be three pixels each.
Press start, then play a note.
The microphone is used only while you are tuning. Nothing is recorded and no audio leaves your device.
A4 = 440 Hz is the international standard and the right default. Some ensembles tune slightly differently by convention; no reference pitch is acoustically or scientifically superior to another.
More music tools
Microphone not working? Check it with the microphone test. Hearing nothing from the reference tones? Try the sound test.
What this can honestly do
It tells you which note is sounding, what frequency it is, and how far that sits from equal temperament in cents. That is genuinely useful for a digital keyboard, for finding the one note on an acoustic piano that has drifted badly, for checking an instrument before you buy it, and for learning what cents actually sound like.
What it cannot do, and why
It cannot tune an acoustic piano, and no browser tool can. Three reasons, all real:
Stretch tuning. A piano is not tuned to the equal-tempered numbers shown here. Real strings are stiff, so their harmonics sit slightly sharp of perfect multiples - a property called inharmonicity. To make octaves sound right, a tuner deliberately sets the top of the instrument sharp and the bottom flat, following a curve unique to that piano's scale design. Tuned to the mathematical figures instead, a piano sounds subtly wrong across its range.
Unisons. Most notes have two or three strings. They must be tuned to each other so precisely that they sound as one; a few cents apart and the note wavers. That is done by muting strings with a felt strip and listening, not by reading a number.
Pins and mechanics. Tuning pins are driven into a wooden pinblock and need a proper lever, controlled technique and a feel for setting the pin so it holds. Overturning one can crack a block or break a string under considerable tension.
A piano technician does all three. If your piano sounds wrong, call one - it costs less than the damage from a first attempt.
Using the key strip
Two octaves show at once, with a selector to move the window. All 88 keys on a phone would be three pixels each, which helps nobody. Tap any key to hear its reference pitch.
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Quick answer
Press start, play a single key and let it ring. The detected note lights on the key strip with its frequency and cents deviation. This checks notes - it cannot tune an acoustic piano, which needs a technician.
Key facts
- Shows note, octave, frequency and cents on a key strip
- Two octaves at a time, with an octave selector
- Reference tone for any key
- Equal temperament with adjustable A4
- Cannot replace professional piano tuning - stretch tuning and unisons need a technician